1. Field of the Invention
This invention relates to the production of filaments and fibers from filament-forming acrylonitrile polymers characterized by improved comfort.
2. Description of the Prior Art
Acrylonitrile fibers and fabrics prepared therefrom possess many desirable attributes. However, their lack of "comfort" has severely limited penetration of the cotton and wool markets. "Comfort" as defined herein refers to the ability of a fiber to transfer body moisture from the inside of a garment made therefrom to the outside where it can evaporate. Because of the large market potential there is a great interest in methods for increasing the "comfort" of acrylonitrile fabrics. The best method of increasing "comfort" is to incorporate a suitable additive into the acrylic solution before spinning. Common additives include anionic and cationic as well as nonionic surfactants, such as polyether polyols. While these surfactants increase the comfort of acrylonitrile polymer fabrics, they dissolve out of the fiber during the quench step of the solvent spinning process and during laundering. Loss of the surfactant into the quench bath is particularly serious because it makes recycling of the bath difficult and presents a waste disposal problem. Loss of the surfactant during laundering obviously decreases the value of the product to the consumer.
The following patents are pertinent to the instant invention:
U.S. Pat. No. 4,239,722--relates to a process for production of filaments and fibers from filament-forming synthetic polymers by spinning a solution which, in addition to a suitable solvent, contains from 5 to 50 percent by weight of a substance which is essentially a non-solvent for the polymer. The preferred filament-forming synthetic polymers are acrylonitrile polymers and the non-solvent additives include, in a list thereof, ethers and esters of polyhydric alcohols. There is no disclosure of the use of polyols cross-linked with polyisocyanates and the materials are deliberately selected so that they can be washed out of the filaments with a washing liquid.
U.S. Pat. No. 3,474,061--relates to a method for preparation of a stable system suitable for treating textiles wherein a cross-linkable polymer which contains certain listed groups, which list includes urethane, imide, amide, hydroxy, carboxy groups, etc., is mixed with a cross-linker prepared by reacting an alkoxymethyl isocyanate with a compound having at least 2 active hydrogen atoms. The cross-linked material apparently is applied only as coatings on textiles and does not incorporate the isocyanate cross-linked additive or any other additive into the fiber solution before spinning.
U.S. Pat. No. 4,264,645--relates to a treating agent which may be a polyether with a molecular weight of between 500 and 8500, and an ethylene oxide content of about 35 to 80 weight percent and cross-linkable end groups. These may be cross-linked with an isocyanate prepolymer or polyether isocyanate with commercially available mixtures of TDI preferred. This material is not incorporated into an acrylic solution before spinning but rather is applied to a substrate, particularly fleece-based artificial leathers, from an aqueous solution.
U.S. Pat. No. 3,329,557--relates to dispersing a high molecular weight poly(alkylene ether) in a melt-spinnable synthetic polymer which is then melt spun and drawn to provide a textile filament. There is no disclosure of cross-linking the polyalkylene ether and the purpose is to increase antistatic properties.
British Pat. No. 1,151,942--relates to a process for the production of polyester filaments and fibers wherein a water-soluble polyester is added to the polyester to be spun before the spinning process. The water-soluble polyester is subsequently washed out after the spinning process. There is no suggestion of cross-linking of any kind and particularly no disclosure of cross-linking with an isocyanate.